This project will develop new synthetic technology for radiolabeling receptor bioligands with technetium (Tc) and rhenium (Re) for diagnostic and therapeutic applications in nuclear medicine. The overall goal of the project is to provide a convenient new method which functions as an "instant kit" and avoids the need for difficult additional chromatographic steps to purify radiolabeled receptor ligands that are required with other methods of radiolabeling. The key conceptual difference of our approaches resides in the use of synthetic polymer-supported bioligands w2hich react with the metal Tc/Re to form organoimido complexes. The project focuses on synthesizing three specific biomedically relevant bioligand-receptor systems: i) biotin for tumors expressing SSTRs; iii) tropane analog for dopamine transporter receptors and the detection and treatment monitoring of Parkinsonian disease. The chemistry of the labeling reaction of these systems will be developed using stable isotope rhenium complexes, which is an accepted surrogate for 99mTc/188Re radionuclides. The structures, chemical properties, and receptor binding affinities of these product complexes will be determined. The polymer supported systems synthesized in this project will be available for labeling studies with 99mTc and 188Re. The successful implementation of this methodology will be a major advance towards t he practical application of Tc/Re radiopharmaceuticals for diagnostic imaging and therapy.